simple pendulum
differential eqn of motion
theta'' + g/l * sin(theta) = 0
l is const, g is gravity
if theta < 14 deg, sin(theta) ~~ theta -> theta''+g/l*theta = 0 -> w = sqrt(g/l), f=w/2pi

problems to overcome:
	getting osc started
	keeping it at a specific freq
	sustained oscillation
	achieve predictable amp of osc w/o distortion

looking at colpitts mosfet osc, 2 caps and 1 inductor, inductor across GD, caps otherwise, load resistor
it's a positive feedback network tacked onto an amp

math:
describing functions
non-linear dynamics
have to set q point with DC bias circuitry

kinetic energy in inductor: Lii/2
kinetic energy in capacitor: CVV/2

research going into microminiature inductors as spiral and square spiral inductors
must be careful not to dip into triode or cutoff because it causes clipping

small sig equiv circuit: lots of fun
equations simplify to:
	Vo(sC1 + 1/R' + 1/Ls) + Vgs(gm-1/Ls) = 0
	Vgs = Vo/(1+LC2ss)

combine for: Vo(gm+sC2 + (1+ssLC2)(1/R'+sC1)) = 0
Vo != 0 to start osc
set rest to 0 -> sssLC1C2 + LC2ss/R + (C1+C2)s + (gm+1/R') = 0
replace s with jw
rework to get w = sqrt((C1+C2)/LC1C2)
generally, gmR' >= C2/C1
want to restrict resonance as much as possible
figure of merit, Q=energy consumed/(power dissipated per cycle * 2pi) = wL/R' (shows width of curve in freq domain)

derive osc freq for hartley osc, also condition to set osc